The present invention relates to a disk rotating apparatus and, more particularly, to a constant linear velocity disk rotating apparatus for rotating disks, such as video disks and digital audio disks, carrying video data recorded therein through a constant linear velocity recording process.
The optical disk player is an exemplary apparatus for recording signals such as video signals or audio signals on signal tracks on a disk at a high signal density and for reproducing the signals recorded on the signal tracks.
A disk rotating speed controller for controlling the rotating speed of the disk on such an optical disk player is disclosed, for example, in U.S. Pat. No. 4,223,349. This disk rotating speed controller compares the phase of a signal obtained from the disk and that of a reference signal and controls the rotating speed of the spindle motor of the optical disk player so that the respective phases of the signal obtained from the disk and the reference signal coincide with each other. The sensitivity of detecting the phase error rises toward the periphery of the disk. Therefore, the gain of the amplifier needs to be regulated according to the radial position of the optical pickup, namely, a detector, to regulate the gain of the control system.
It is possible to detect the radial position of the optical pickup with a potentiometer interlocked with the optical pickup. However, employment of a potentiometer for detecting the radial position of the optical pickup requires work for interlocking the potentiometer with the optical pickup and for adjusting the potentiometer and makes the construction of the disk rotating speed controller complex.